The invention relates to the fabrication of water jackets for use with open hearth wood-burning fireplaces for circulating water around the fireplaces, and adapted to be installed with a conventional home heating system. In the past, numerous different types of water jackets have been provided, such as shown in U.S. Pat. No. 3,958,755, and the references cited therein, all of which have been relatively successful in performing their ultimate function. A large part of the expense of such jackets, however, has been the expense of fabrication thereof, and in the past, water jackets have often been fabricated by joining spaced metal plates at their ends and additionally by providing a plurality of plugs between spaced metal plates welded to the plates to maintain proper spacing between the plates in order that the plates are able to withstand the operating pressures encountered. Conventionally, a hole has been punched in one of two plates, a plug welded to the other of the two plates, and the plate with the hole in it placed over the plug and welded to the plug. While such a structure does properly accomplish the desired end result of allowing the water jacket to withstand sufficiently high temperatures and pressures, the fabrication technique requires the formation of two separate welds, and requires the utilization of a plurality of plug numbers.
According to the present invention, the conventional prior art method of water jacket fabrication has been improved by elimination of the plug members conventionally used for spacing the plates and by elimination of one of the welds necessary to affix the plug member in place. According to the present invention, first and second plates are joined together at middle portions thereof; the first metal plate is disposed in a generally horizontal position over an orificed support, and a punching tool is brought into operative engagement with the plate to punch a hole in the plate and simultaneously deform the area around the hole so that the plane of the hole is spaced a given distance S from the plane of the plate. The orificed support preferably comprises a female die portion spaced a distance S' (greater than S) from the plane of the first plate, and during punching and simultaneous deformation the hole is spaced a distance S' from the plane of the first plate with the area around the hole rebounding after removal of the punch. The first plate is then disposed on the second plate so that the plates are generally parallel and so that the area surrounding the hole in the first plate abuts the second plate, and then the plates are joined together spaced apart the distance S by welding around the area defining the hole in the first plate to the portion of the second plate visible through the hole in the first plate. The first and second plates are then joined together with other similar plates to form a water tight water jacket for surrounding an open hearth wood burning fireplace, a water inlet and a water outlet being provided for the water jacket. Preferably, the water jacket includes at least three walls including two side walls and a back wall, and a bottom is provided for the water jacket comprising a header connected between the two side walls and a plurality of wood supporting water conducting pipes extending between the header and the back wall substantially perpendicular to the header, each of the pipes making a small positive angle .alpha. of about 1.degree. to 2.degree. with respect to the horizontal. The header may comprise a prism having a triangular base, which header may be formed by bending a metal plate to form two legs of the triangular base prism, forming a plurality of holes in a straight plate member, attaching the straight plate member to the legs defined by the bent plate, and attaching the pipes in said holes in the straight plate member. The invention includes both the method of fabrication of the water jacket as well as the water jacket constructed according to the method of the invention.
It is a primary object of the present invention to provide an improved fabrication of a fireplace water jacket which is capable of withstanding high pressures of operation. This and other objects of the invention will become clear from an inspection of the detailed description of the invention and from the appended claims.